Polymeric carbothionamides and process for preparing the same



Patented May 21, 1940 POLYMERIC CABBOTHIONAMIDES AND PROCESS FOR PREPARING THE SAME William Edward Hanford, Wilmington, Del, as-

signor to E. I. du Pont de Nemours & Company, "Wilmington, DeL, a corporation of Delaware No Drawing.

Application September 15, 1938,

Serial No. 230,143 9 Claims. (or, 260-551 This invention relates to polymeric organic materials and more particularly to polymeric carbothionamides. The present application is a continuation-in-part of my co-pending application Serial Number l37,l49, filed April 15, 1937.

This invention has as an object the preparation of new polymeric products. A further object is the preparation of polymeric materials useful forthe manufacture of filaments, films, coating compositions, plastics, and the like. further object is the preparation of polymeric carboxylic acid amides in which amido oxygen is replaced by sulfur. Other objects will be apparent from the ensuing description.

Broadly speaking, the above objects are accomplished by reacting under polymerization conditions certain bifunctional compounds having mutually reactive .carbothionamideforming groups. More specifically, the objects of the invention are accomplished by reacting together ingredients comprising at least two molecules of i at least one compound having two and only two 'carbothionamide functions, said functions, when both are nitrile, being separated by a chain of at least three contiguous carbon atoms, and when comprising primary amino by a chain of at least two contiguous carbon atoms, said compound or compounds being so chosen that the carbothionamide functions in at least one-of them comprise at least one primary aliphatic amino group, being further so'chosen that there is present an equal number of complementary carbothionamide functions, and being further so chosen that the structural unit formed will have a chain length of at least seven. Still more specifically, the objects of the invention are. accomplished in one way by reacting hydrogen sulfide with at' least two molecules of at least one compound containing two and only two carbothionamide functions selected from the class consisting of nitrile and primary aliphatic amino, said functions when both are nitrile being separated by a chain of at least three contiguous carbon atoms and when comprising primary aliphatic amino by a chain of at least two contiguous carbon atoms, said compound'or compounds being further so selected' that there is present an equal number of nitrile and primary aliphatic amino groups, and

being further so selected that the structural unit formed will have a chain length of at least seven. The reaction, in order to obtain useful fiberforming products, is preferably continued until a product having an intrinsic'viscosity, as defined below, of at least 02 is obtained.

By the term carbothionic acid is meant an acid having a s JE-OH group, and, by the expression amide of a carbothionic acid" (or more briefly carbothlonamide), a thioamide having the structure By secondary carbothionamide is meant a thioand isothiocyanate, which will react with another compound or compounds to form the carbothionamide structure.

' The term complementary, as applied to carbothionamide functions, is used to mean a function of type opposite to that. of the function with which it is complementary in that the two are both required for producing: the carbothionamide. Thus, primary aliphatic amino and isothiocyanate are complementary, as are primary aliphatic amino and nitrile, in the presence of hydrogen sulfide.

By the word contiguous" is meant that the chain carbon atoms referred to are all in the chain of atoms of which the functional groups are a part.

By structural unit" is meant that chemica unit of structure which repeats itself or recurs in the polymer; it might be called the "least common divisor of the polymer, and is readily determinable by a simple inspection of the formu nc-cnz-cm-cm-cm-cn and of radical length six, reacts with hydrogen sulfide and ethylenediamlne, of the formula HzN-CHz-CHz-NH:

and of radical length four, to eliminate two molecules of ammonia (the ammonia nitrogen being originally the nitrile nitrogen) and to give a polymeric carbothionamide having a structural unit of, unit length ten. The radicalleng'th, then, of a 'dinitrile will'be the number of carbon atoms in the chain, including the nitrile carbons; that of a monoaminomononitrile will be the total number of chain atoms, including the amino nitrogen but excluding the 'nitrile nitrogen; that of a di- 6 isothiocyanate will be the total number of chain atoms, exclusive of the two isothiocyanate sulfur atoms; and that of the primary aliphatic diamine will be the total number of chain atoms between and including the amino nitrogens, regardless of the compound with which it is reacted.

By intrinsic viscosity, as appliedto the polymers of certain .of the examples, is meant the mathematical quotient log e Nr where Nr is the viscosity of a dilute (e. g., 0.5%) solution of the polymer in a suitable solvent (e. g., m-c'resol) at a convenient temperature (e. g., 25 C.) divided by the viscosity of the same solvent in the same units at the same temperature, and C is the concentration in grams of polysimplicity, they have been and will be discussed.

only as amides of carbothionic acids. Such products are always obtained if the reactants are chosen as indicated above. However, depending upon the classes of reactants selected, the

products fall into two well-defined groups: (A) polymeric amides of dibasic carbothionic acids and diprimary diamines, and (B) polymeric amides of primary vmonoaminomonocarbothionic acids. Type (A) may be further subdivided into (a) polymeric amides of thiocarbonic acid (i. e., polythiocarbamides or polythioureas) which are obtainablefromone or more diprimary diamines and one or more diisothiocyanates, and (b) polymeric amides of dicarbothionic acids, which are obtainable from one or more dinitriles, hydrogen sulfide, and one or more diprimary diamines. Type (B) is obtainable from hydrogen sulfide and one or more primary monoaminomononitriles. The reactions by which these several types are formed may be represented generally as follows. The various R's represent divalent radicals of appropriate chain lengths, and the .Ds the number of participating molecules:

Aminonitrile polymer It is to be noted that in type (B) above, the two molecules having two carbothionamide functions are molecules of the same compound. In such a case, of course, the functions must be complementary. By definition one of them must be primary aliphatic amine. The other therefore may be nitrile (illustrated), inwhich case hydrogen sulfide is required as an additional reactant, or it may be isothiocyanate, in which case no 1| additional reactant is needed.

As already indicated, in order that linear polymeric products be obtained, the reactants must be so chosen that the structural unit which will be formed will have a unit length of at least seven and preferably of at least eight. This unit length is determinable from the radical lengths of the reactants, which in turn can be readily ascertained by an inspection of their formulas as hereinbefore explained. Even when the length of the structural unit is seven, some cyclization takes place; therefore best yields of polymers are obtained when compounds are used whose sole or joint radical lengths, as the case may be, are at least one higher than the minimum.

It is further to be noted that the functional groups, when both are nitrile groups, should be separated by a chain of atleast three contiguous carbon atoms, and when one is a primary aliphatic amino group or both are primary aliphatic amino groups, by a chain of at least two con tiguous carbon atoms. This is due in part to the fact that compounds not so qualified are unknown or in some way unsuitable. This requirement will automatically cause the diaminedinitrile and diamine-diisothiocyanate products to have structural units of length greater than seven. Similarly, it will be seen that, in the case of aminonitriles, the requirement is itself taken care of by the limitation on minimum unit length of the structural unit.

Products of group (A), subgroup (b) are made in general as follows: Exact chemical equivalents of diamine and dinitrile are mixed in a suitable vessel, and to this mixture is added a diluent such as phenol which is a solvent for the product and chemically inert, under reaction conditions, to reactants and product. Gaseous hydrogen sulfide is then passed in at IUD-200 C. under such conditions that ammonia and excess hydrogen sulfide may escape without substantial loss of diamine or dinitrile' This is continued until substantially no more ammonia is evolved. The polymer may then be isolated from the viscous solution which has formed-by removing the solvent in vacuo or by pouring the solution into a liquid such as ether which dissolves the solvent but not the polymer.

The products of group B are made in general in the same way, i. e., the aminonitrile is placed in contact with an appropriate inert solvent for the product, and hydrogen sulfide passed in at elevated temperature until evolution of ammonia has substantially ceased. The polymer is then isolated by distilling off the solvent or by adding the solution to a liquid which dissolves the solvent but not the polymer.

Products of group (A), subgroup (a), i.e.,po1ymeric amides of thiocarbonic acid or polythiillustrated by the following examples, wherein parts given are by weight. Examples I-VI inclusive illustrate group (A), subgroup (b) above; Examples VII-IX inclusive illustrate group (B); and Example X illustrates group (A), subgroup (a). The invention of course has many other specific embodiments.

Exunu I Polymeric ethylenethioadipdmide 'Adiponitrile (21.6 parts, 0.2 mol) and ethylenediamine (12.0 parts, 0.2 mol) in phenol (50 parts) are heated five hours at 100 C. and thirty minutesat 130 C., while hydrogen sulfide is bubbled through the solution. The

phenol is removed by distillation under diminished pressure, the bath temperature being increased to 180 C. The polymeric product obtained may be formed into films when flowed from organic solvents and baked 18 hours at 100 C.

Exlmrts II Polymeric decametliylenethiosebacamide Sebaconitrile (32.8 parts, 0.2 mol) and decamethylenediamine (34.4 parts, 0.2 mol) in phenol (120 parts) are heated five hours at 100-120 C. "while hydrogen sulfide is bubbled through.

An additional 250-300 parts of phenol is added. the solution warmed until uniform, and poured into ether. The polymeric product separates as a cream-colored gum from which volatile products may be, steamdistilled. dried under 26 inches of vacuum at 110 C. for 18 hours. The polymer thus obtained softens at 45-50 C., is dark brown in color, and is very rubbery.

EXAMPLE III Polymeric decamethylenethiosebacamide Sebaconitrile (16.4 parts, 0.1 mol) and decamethylenediamine (17.2 parts, 0.1 mol) are dissolved in dioxan (50 parts) and heated seven hours at 90-100 C., during which time hydrogen sulfide is bubbled through the solution. The dioxan is removed under diminished pressure, leaving a solid yellow polymeric product which softens at 85-90 C. Films cast from pyridine or dioxan solutions of this polymer and baked .18 hours at 100 C. are clear and tough.

EXAMPLE IV Polymeric hexamethylenethioadipamide and insoluble in toluene.

Exmtn V I Polymeric decamethylenetllioterephthalamide Decamethylenediamine (18.0 parts, 0.105 mol) and p-dicyanobenzene (12.8 parts, 0.1 mol) are heated in 135 parts of butoxyethanol for two Y hours at 140 0., during which time much sub- I limation occurs. The heating is continued for eight hours at 90-100 0., hydrogen sulfide being passed through during both periods of heating.. After the solution has stood for 18 hours,

a solid polymeric product precipitates and is filtered and washed with ethanol. It consists of 23 parts of a light yellow powder, insoluble in hot alcohol and toluene. This polymer decomposes slowly at 175 C. and melts completely at 190 C.

The residue is ExummVI v Polymeric decamethylenetbioseba'camide In a pressure vessel are placedv 16.4 parts;of sebaconitrlle, 17.2 parts of decamethyleriedii amine, and 80'parts of absolute ethyl alcohol. This mixture is saturated'with hydrogen sulfide at room temperature, causing separation of a white salt. The pressure vessel is now sealed, heated for 8 hours at 100 C., and then opened.

On evaporating out the alcohol, a very light -hol, and carbon tetrachloride. It is, however,

sparingly soluble in pyridine.

Exmm VII Self-polymer of w-amiiiothiocapric acid prepara tion with toluene as solvent Twenty-eight (28) parts of w-aininocaprinitrile (HzN(CHz)oCN) is added to an excess of liquid hydrogen sulfide in 22 parts of dry toluene at 'l0 C. to -80 C. A white salt-like material begins to. separate immediately. After all of the aminonitrile has been added, the resulting toluene slurry is transferred to a steel bomb at room temperature, which is then sealed and heated for twelve hours at 150 C. When the bomb is cooled and opened, a yellow crumbly product is found to have separated from the toluene solution. This polymer, after filtration to remove toluene, softens at 65 C. and melts at 110 C. When fused, it can be drawn into short filaments. This polymer is soluble in pyridine, phenol, and benzyl alcohol, is slightly soluble in p-methoxyethanol, and is insoluble in.

methanol, absolute ethanol, and dioxan. Its neutralization equivalent, as determined by titration with m-cresolsulfonic acid, in m-cresol solution using m-Cresol Purple as indicator, is 1900.

To effect further polymerization of the above relatively low polymer, it is'heated at 110 C. to 120 C. in an atmosphere of hydrogen sulfide for one and one-half hours and then for an additional hour at 180 C. It is then dark and resinous, softens at 65 C., melts at 120 C.,' is soluble in hot phenol and hot ethylene chlorohydrin, partly soluble in hot diethylene glycol and hot cyclohexanone and insoluble in ethylene glycol, butanol, dioxan, and cyclohexanol. When molten it may be drawn into filaments by touching with a cold rod and withdrawing the rod. These filaments show .a permanent deformation when cold drawn and form crinkly filaments when the tension is released. The intrinsic viscosity of the polymer, determined in m-cresol, is 0.21, and the neutralization equivalent, as-determined by titration with m-cresolsulfonic acid, in m-cresol solution using m- Cresol Purple as indicator, is 1660.

Ermine VHI Self-polymer of w-am inothiocapric acid preparation with a phenolic solvent Fifty (50) parts of w-aminocaprinitrile is placed in a steel bomb with 90 parts of crystalline phenol. Hydrogen sulfide is admitted at 250 lbs/sq. in. pressure; the bomb is sealed; and the mixture is heated for twelve hours at 150 C. After cooling and opening, a solution which is liquid at room temperature is found to be present. This solution isadded to 110 parts of melted phenol and the mixture poured into 640 parts of well -stirred alcohol. A rubbery mass separates. The neutralization equivalent of the polymer, as determined by titration with m-cresolsulfonic acid, in-m-cresol solution using mCresol Purple as indicator, is 2200.

EXAMPLE IX Self-polymer of w-aminothiocazm'c acid preparation without solvent precipitated by adding this solution to*80 parts of diethyl amine, 1,6-diphenylhexamethylenediamine, and.

well-stirred ethanol. The tan-colored powder so obtained, after drying in the air, melts at 105 C. This polymer can be melt spun into filaments. Its neutralization equivalent, as determined by titration with m-cresolsulfonic acid, in m-cresol solution using m-Cresol Purple as indicator, is 1660.

' EXAMPLE X Polymeric decamethylene thiourea To 7.95 parts of decamethylene diisothiocyanote in 140 parts of ether is added 5.34 parts of decamethylenediamine in 59 parts of ether. The white precipitate which separates after a short time is filtered off and washed with ether, 12 parts being obtained. It is insoluble in alcohol, soluble in m-cresol, melts at 115 C., and is presumably a low polymer. To efiect further polymerization, it is dissolved in 15 parts of cresol and heated eight hours'at 200-C., during which time some hydrogen sulfide is evolved. The cresol solution is washed with alcohol, giving a product which stillmelts at 115 C. and which has an intrinsic viscosity of 0.31. When fused, the polymer can be drawn to an elastic filament by touching with a cold rod and removing the rod. The polymer is insoluble in dilute sodium hydroxide, dilute hydrochloric acid, and glacial acetic acid. In the subgeneric form of the invention illustrated in Examples I to VI, I may employ any diamine in which both amine groups are primary,

attached to aliphatic carbons, and separated by a chain of at least two carbons contiguous therewith. Similarly, I may use any dinitrile in which the nitrile groups are separated by a chain of at least three atomscontiguous therewith. These minimum chain lengths of nitrile and amine automatlcally take care of the requirement, hereinbefore mentioned, that the reactants be so selected as to yield a product having a structural unit of length at least seven. Suitable specific amines include: hexamethylenediamine, decamethylenediamine, wf-bisaminopropyl ether, tetramethylenediamine, pentamethylenediamine dodecamethylenediamine, 3'-methylhexamethylenediamine, ethylenediamine, trimethylenediamine, propylenediamine, 1,4-diaminocyclohexane, p-xylylenediamine, octadecamethylenediamine, p,p'-diaminodiethyl ether, B,p'-diaminosulfide, 1,6-dimethylhexamethylenedi- 1,12-diaminooctadecane; Suitable specific dinitriles include those of the following acids: adlpic,

arcane sebacic, suberic, azelaic, a-methyladipic, dilactylic, diglycolic, diphenic, p,p'-benzophenonedicarboxylic, quinolinic, thiodiglycolic, terephthalic, naphthalic, glutaric, a,'-dimethyladipic, isophthalic, p-tert-amyladlplc, 1,4-naphthalenedicarboxylic,' '-thiodibutyric,v,-y-sulfonedibutyric, p-cyclohexyladipic, and pinic. which the nitrile groups are separated by only two contiguous carbons, such as o-phthalonitrile and maleonitrile, are not suitable for preparing polymeric carbothionamides since they react with hydrogen sulfide and diprimary diamines to form monomeric imidothioimides.

In the subgeneric form of the invention illustrated in Examples VIIIX, I may use any primary aliphatic monoaminomononitrile having a radical length of at least seven. Suitable specific nitriles include those of the following acids: waminononanoic, w-aminoundecanoic, w-aminoheptadecanoic, l2-aminooctadecaneic, p-aminomethylbenzoic, p aminomethylhydrocinnamic, IO-aminodecanoic, Z-methyl-G-aminohexoic, 6- methyl- 6 -aminohe xoic, 'y-amino- '-carboxydipropyl ether, and the like.

Reference is made to my joint application, Serial Number 230,145 for other specific diisothiocyanates and diamines which may be used in that form of the invention illustrated in Example X, and for other types of reactants that combine to form polythioureas.

In that embodiment of the invention illustrated Dinitriles in by Examples I-IX, I may use as inert solvents,

range from '75 to 300 C., but should preferably be from 100-200 C. Pressures may .vary from 1 to 100 or more atmospheres. The hydrogen sulflde is preferably passed through the reaction mixture for the duration of the reaction, but, it.

the processis operated on a small scale, the other reactants may simply be dissolved in a solvent,

the solution saturated at 025; C. with hydrogen sulfide, and the saturated solution heated in a closed system. The amount of hydrogen sulfide may be one mol or more per nitrile group. In general it is 'best to use a large excess of hydrogen sulfide and recover the unreacted portion. The proportions of diamine and dinitriles (Examples I-VI) should be very nearly chemically equivalent in order to obtain high molecular weight polymers. By changing the ratio markedly in either direction, lower molecular weight products are secured.

Reference is made to my joint application, Serial Number 230,145 for other conditions for carrying out that form 0! the invention illustrated in Example X.

The preferred process of the invention comprises the reacting of the primary aliphatic amine group with the nitrile group and hydrogen sulfide.

.As already explained, this amine group may be Ho-cs-w-cs-orr (or or dicarbodithioic acids of the rormuia ns-cs-a -cs-sn). a a a divalent hydrocarbon radical having at least two carbons in the chain of which the amino nitrogens' are a part, the carbons adjacent to R being aliphatic in character. R is a divalent hydrocarbon radical having at least three carbons in the chain (or shortest chain) of which the nitrile groups are a part. A still more select group'of thioamides are those of polymethylenediamines in which both amine groups are primary and polymethylenediamines .in which both amine groups are primary and polymethylene dicarbothionic acids. Specifically R may be tetramethylene, pentamethylene, hexamethylene, decamethylene, a-methylhexamethylene, p methylhexamethylene, a,a'-dimethylhexamethylene, ,a-diphenylhexamethylene, a-octyldodecamethylene, ethylene, propylene, p-xylylene, 1,4-cyclohexylene, and the like. Specifically, B. may be any of the radicals just given for R or it may be an arylene radical such as p-phenylene, m-phen'ylene, 2,4-

tolylene, 1,4-naphthylene, p,p'-diphenyl, and the like, Among. the specific thioamides thus included are polymeric decamethylenethiosebac- The above description and examples are in tended to be illustrative only. Any modification of'or variation therefrom which conforms to the spirit of the invention is intended to be included within the scope of the claims.

I claim:

1. A linear polymeric carbothionamide.

2. A linear polymeric secondary amide of a carbothionic acid.

3. A linear polymeric secondary amide of a carbothionic acid capable of being drawn into a fiber.

4. A polymeric amide of a bifunctional carbothionic acid and a bifunctional primary amine, the primary amino groups of which are bound to aliphatic carbon atoms, which amine may be the same compound as the carbothionic acid,

the functional groups of said bifunctional compound or compounds being separated by a chain of at least three contiguous carbon atoms, 'when both are nitrile groups, and by a chain of at least two contiguous carbon atoms otherwise, said amide having a unit length of at least seven.

5. A polymeric amide of a dicarbothionic acid and a diaminein-whichboth amino groups are primary and attached to aliphatic carbon atoms, the acid groups of said acid being separated by a chain of at least three contiguous carbon atoms, and the amine groups of said amine by a chain of at. least two contiguous carbon atoms.

6. Process of preparing polymeric carbothionamides which comprises reacting together ingredients comprising at'least one compound having two and only two carbothionamide functions, said functions when both are nitrile being separated by a chain of at least three and otherwise by a chain of at least two contiguous car-- bon atoms, said compound or compounds being so chosen that the carbothionamide functions in at least one of them comprise at least one primary aliphatic amino group, so chosen that there is present an equal number of complementary 'carbothionamide functions, and so. chosen that the structural unit formed will have a chain length of at least seven. '7. Process for preparing polymeric carbothionamides which comprises reacting together in gradients comprising at least one compound having two and only two carbothionamide functions, said functions when both are nitrile being separated by a chain of at least three'and otherwise by a chain of at least two contiguouscarbon atoms, said compound or compounds being so chosen that the carbothionamide functions in at least one of them comprise at least one primary aliphatic amino group, so chosen that there is present an equal 'number of complementary carbothionamide functions, and so chosen that "the structural unitformed will have a chain length of at least seven and continuing the reaction until the product has an intrinsic viscosity of at least 0.2. I

8. Process for preparing polymeric carbothionamides which comprises reacting hydrogen sulfide with at least two molecules of at least one compound containing two and only two carbothionamide functions selected from the class consisting of nitrile and primary aliphatic amino,

said functions when both are nitrile being separated by a chain of at least three and otherwise by a chain of at least two contiguous carbon atoms, said compound or compounds being further so selected that there is present an equal number of nitrile and primary aliphatic amine groupaand further so selected that the structural unit formed will have a chain length of at least seven. I i

9. Process which comprises reacting hydrogen sulfide with a diamine in which both amino groups are primary, attached to aliphatic carbon atoms, and separated by a chain of at least two contiguous carbon atoms, and a dinitrile in which the nitrile groups are separated by a chain of at least three contiguous carbon atoms.

WILLIAM EDWARD HANFORD. 

